Transcript G070713-00

advanced
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Advanced Virgo
BASELINE DESIGN
Giovanni Losurdo – INFN Firenze
Advanced Virgo Coordinator
for the Virgo Collaboration
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ADVANCED VIRGO (AdV)
GOALS:
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Sensitivity: about 10x better than Virgo
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Timeline: be back online with AdvLIGO
LSC/Virgo Meeting – Hannover, Oct 22, 2007
MAIN CHANGES:
–
higher power
–
signal recycling
–
heavier mirrors
–
better coatings
–
beam geometry
G.Losurdo – INFN Firenze 2
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ONGOING AdV R&D – SUMMARY (I)
Mirror coating
Mirror cleaning
Optical config. design
(Post-doc@B’ham)
Fiber laser and IMC
New modal optics
Prototyping/locking
(CALVA)
Optics for
high power
Detection system
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 3
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ONGOING AdV R&D – SUMMARY (II)
Tiltmeter
IP upgrade
New payload design
Ribbons for
monolithic susp.
(Glasgow)
Electrostatic act.
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 4
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STATUS
AdV conceptual design completed
–
Internal review in progress
–
Due to STAC (advisory panel) and EGO Council (funding agencies) this week
Waiting for the funding agencies approval:
–
New organization being setup. From Working Groups to WBS.
–
Next two years to prepare the AdV technical design.
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 5
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AdV BASELINE
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LASER
BASELINE:
200 W SOLID STATE LASER AMPLIFIER (LZH)
Nice Group is already collaborating with LZH for the Virgo+ amplifier.
ALTERNATIVE OPTION:
FIBER LASER AMPLIFIER: promising research line
– stabilization to be done
– non linear effects and polarisation maintaining to be investigated with high power
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 7
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INPUT OPTICS
BASELINE:
144 m SUSPENDED RESONANT IMC: Virgo-like solution. Problem of small
angle diffused light to be addressed.
ALTERNATIVE OPTION:
FIBER LASER IMC: promising research
line, would be a major simplification.
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 8
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INPUT OPTICS

A dedicated facility being setup at EGO to test the input optics for
Virgo+/AdV with high power. 200 W Yb laser available
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Tests on Faraday with passive thermal compensation (DKDP) and EOM (RTP)
to start in fall 2008
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 9
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OPTICAL CONFIGURATION
BASELINE:
DUAL RECYCLED INTERFEROMETER – Optical parameters to be defined.
The base for the SR
tower is there!
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 10
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BEAM - DETECTION
OPT. LAYOUT BASELINE:
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TEM00
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WAIST IN THE CAVITY CENTER
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LARGER BEAM: requires changing
the vacuum links in the central area.
ALTERNATIVE OPTION:
HIGH ORDER LAGUERRE MODES
DET. BASELINE:
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PHOTODIODES IN VACUUM
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DC DETECTION
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 11
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LSC/Virgo Meeting – Hannover, Oct 22, 2007
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PIPE Ø = 600 mm
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VALVE Ø = 500 mm
G.Losurdo – INFN Firenze 12
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MIRRORS
BASELINE:
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35 cm Ø, 20 cm thick, 42 Kg FP mirrors
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Larger BS (55 cm Ø – TBC)
______________________________
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STATE OF THE ART COATING (R&D in
progress)
ALTERNATIVE OPTION:
35 cm Ø, 30 cm thick, 63 Kg FP mirrors
Useful if fiber geometry is optimized
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 13
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MIRRORS
POLISHING
– Flatness, one of the main limitations in Virgo (with cleanliness!)
– Need for better polishing and more precise geometry (r.o.c.)
– Corrective coating
METROLOGY
– Characterization benches available at LMA
– Modification needed to handle larger mirrors (BS)
– Better metrology  better corrective coating
CLEANLINESS
– Keep losses in the sub-ppm range
– Proper protection of mirrors surface during installation
– Maintain cleanliness at the site requires the installation
of a laminar flux in the towers
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 14
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SUPERATTENUATOR
BASELINE:
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VIRGO DESIGN with STIFFER IP LEGS
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TILTMETER AND IP 6 DOF CONTROL
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MECHANICS: NEW MARIONETTE REFERENCE MASS
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MIRROR ACTUATION: COIL-MAGNET PAIRS
ALTERNATIVE OPTION:
ELECTROSTATIC ACTUATORS: noise specs to be
demonstrated
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 15
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SUPERATTENUATOR
q
PZT
tiltmeter
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Virgo inertial platform controlled in 4 d.o.f.
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Wind induced ground tilt proved to be a problem
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AdV: implement tilt control
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 16
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SUSPENSIONS
BASELINE:
FUSED SILICA CYLINDRICAL FIBERS
ALTERNATIVE GEOMETRIES:
FUSED SILICA RIBBONS
DUMBBELL FIBERS
Virgo+ activity:
dummy mirror
suspended with
silica fibers
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 17
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AdV BASELINE - SUMMARY
heavier mirrors
(42 kg)
new IP
tilt control
high finesse
(≈1000)
larger beam waist
new payload
signal recycling
high power SSL
(200 W)
fused silica
suspensions
DC detection
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 18
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SENSITIVITY CURVE - preliminary
DESIGN PARAMETERS:
– SR mirror transmittance: 0.04
– Input mirror transm: 0.007
– Finesse: 885
– PR factor: 23.5
– Power on BS: 2.9 kW
BNS range: 121 Mpc
BBH range: 856 Mpc
1 kHz sens.: 6 10-24/√Hz
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 19
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AdV sensitivity vs Fiber geometry
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The ribbon choice reduces considerably the contribution of
suspensions thermal noise
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Dumbbell fibers can also improve the performance
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The benefits on the sensitivity are limited by radiation pressure,
newtonian and CONTROL NOISE (unmodelled so far)
fiber
geometry
cylindrical
ribbon
Finesse
885
G
23.5
PBS
2.9 kW
BNS
121
126
BBH
859
959
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 20
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HEAVIER MIRRORS?
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If ribbons are used, low frequency sensitivity can be further improved
by using thicker mirrors (30 cm diam., 63 kg mass)
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The low frequency sensitivity is then limited by newtonian noise
(model uncertain) and coating brownian noise
fiber
geometry
BASELINE
ribbon
63 Kg mirr
Finesse
885
G
23.5
PBS
2.9 kW
BNS
121
130
BBH
859
1053
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 21
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TWO-STEP STRATEGY?
We are considering the idea of a two-step strategy:
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Start AdV WITHOUT SR mirror and learn to operate the power recycled
interferometer with high power
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Add the SR mirror afterwards
A good “intermediate” sensitivity can be achieved, even better with
heavier mirrors
Power rec AdV
BNS range: 97 Mpc
BBH range: 265 Mpc
1 kHz sens.: 2 10-23
Dual rec AdV
BNS range: 121 Mpc
BBH range: 859 Mpc
1 kHz sens.: 6 10-24
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 22
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SUMMARY
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A baseline design for AdV has been proposed
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Possible changes to the baseline will be considered (on the strength of
the R&D progress) and discussed next year within a new AdV
organization
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Important design parameters to be decided next year
We look forward to an intense exchange
with LSC to make the best possible design of AdV
LSC/Virgo Meeting – Hannover, Oct 22, 2007
G.Losurdo – INFN Firenze 23